Collapsible pipe tap



17, 1935. A, E 'DRlSSNER Er AL 2,024,278

' K COLLAPSIBLE PIPE TAP Filed March 2e, 1935 7 sheets-sheet "1 Dec. 17, 1935'. A E, DRBSNER AL 2,024,271;

4coLLAPsILE PIPE TAP Fngled Maron ze, 1955 7 sheets-sheet 2 Tll l Hh. N n s. wh...

50996665. 5ml/551m YShVeets-Sheei; 3

Dec. 17, 1935. A. E; DRlssNER Er'm. COLLAPSIBLE PIPE TAP Filed March ze, 1935 A. E. DRISSNER nEl' AL 2,024,278

COLLAPSIBLE PIPE TAP U Filed March 26,'1935 l '7 sheetvsneet 4 v Dec.-l 7, 1935- A. E. DRlssNER Er AL COLLAPSIBLE PIPE -TAP T-Sheets-Sheet 5 Filed March 26, 1955 COLLAPSIBLE PIPE TAP Filed March 26, 1935 7 SheelZS--Shet-Bl'l 6 Dec-,17, 1935v A. E. DRlssNER ET AL '2,024,278

COLLAPSIBLE PIPE TAP Filed March 26, 1955 7 sheets-sheet 4Patented Dec. 17,- 1935 unimo STATES coLLArsmLn PIPE TAP Alfred E. Drissner and william a. Hogg, 'cleveland, Ohimassignors to The National Acme Company, Cleveland, Ohio h10, a A corporation of Application March 26. 1935, Serial No. 13,106

23 claims.,

This invention relates to taps, particularly to pipe taps adapted for the threading of large pipes such as oil-well pipes usually having a diameter of about six to fourteen inches, the object of the a invention being to provide an improved collapsible or receding pipe tap having automatically shiftable c-ircular cutters or chasers for cutting a tapered pipe thread and which tap is simple construction and efficient in operation.-

A further object is the provision of an improved tap of the type speciiied in which the chasers or 1 cutters are positively and, therefore.' more eilciently controlled especially during their receding movements, thereby insuring that each chaser will do an equal lamount of cutting and be prevented from pulling away from the core piece and so take a heavier cut whereby a better tapered and smoother thread is obtained, and in p which the tap has a minimum number of parts `and yet a large range so that a number of different tapers can be readily obtained and also a fine adjustment oi taper by themere manipulation of very simple adjusting means.

A further object of the invention is the proand having interchangeable nose pieces whereby a varying number of chasers or cutters may be used according to the size of pipe to be threaded. In the drawings accompanying and forming a part of this specification, Fig. 1 is a longitudinal sectional view of this improved pipe tap.

Fig. 2 is also a. longitudinal sectional view at right angles to Fig. 1.

Fig. 3 is an end view partly in section the section being taken on line 3--3 of Fig. l. I Fig. 4 is a cross sectional view taken on line d-ltof Fig. 1.'

Fig. 5 is a front end view of this improved tap. Fig. 6 is a longitudinal sectional view taken on line 6--6 of Fig. 7.

` Fig. 7 is a bottom view of Fig. 6. i Fig. 8 is a detail top view of a part of Flg.'1.

` relation to each other.

Fig..16 is a sectional view of a chaser mounted `on its block, a/id vision of-an improved tap of the type described Fig. 9 is a view of the core member or shank (ci. nio-) I Fig. 1'? is a partial longitudinal section through the hand setting mechanism shown in Fig. 3.

Similar characters of reference indicate corresponding parts in the several views.

Before explaining in detail the present im- 5 provenient and mode of operation thereof, we desiiedto have it understood that the invention is not limited to the details of construction and arrangement of parts illustrated in the accompanying drawings since the invention is capable 10 of other embodiments, and that the phraseology which`we employ is for the'purpose of descrip` tion and not of limitation.` f

The tap is rotated by any `suitable source of power and is fed forward in the way usual in 15 taps-of` this type although the Work may be rotated relative to the tap.

This improved tap, in the preferred form thereof, comprises a housing I within which is located a sleeve l' and within this sleeve is a body 20 or sleeve 2 having a head detachably bolted thereto by bolts 2' (Fig. 1) and both which head and sleeve are herein referred to as the body or sleeve .2: v l

Within this sleeve or. body 2 is a core 25 member or shank 3, on the forward end of which is a hardened tapered core 4 provided with lengthwise extendingv slots 5 of angular form cooperating with similarly formed interlocking slots 6 on the inner ends 1 of the sliding chaser blocks 30 B located circularly around the hardened core- 4 and carried atwthe forward end of the sleeve 2.

These sliding blocks 8 onwhich the chasers are located have their interlocking grooves 6 machined to fit closely in the slots 5 in the core 35 I so that the inward and outward movements of the chasers are controlled in a positive manner and thus a better taper is obtained, also a better form'and smoothness of thread, as each chaser will be' doing an equal amount of cutting and 4.0

cannot pull away from the core and take a heavy y cut.

'I'he chaser blocks 8 are suitably supported in radial recesses 9 of the sleeve or body head 2 for 2), whereby the tapered core 4 is properly and accurately set and held against independent rotation by suitable interlocking meansr such as pins carried by the` core (see Fig. 9).

By means of the interchangeable and detachable core 4, various sizes of cores may be used, thereby permitting any desired number of circular chasers to be used.

The front face of each supporting block 8 is inclined transversely thereto as at 8 (see Fig. 16), wherebythe chasers will be angularly set or inclined to the iront face of the tap body `so that, while the grooves of the .chasers are cut circularly straight and not spirally, they yet have the effect of spirally cut grooves, this inclination of the supporting blocks 8 thus being formed on an angle with relation to the 'front face of the'.

tap body giving the proper angular setting to the circular chasers and controlling the proper cutting edge and clearance thereof.

Each ofthechasers orucutters I Il is substantially circular but with a segmental or sectional part I0 (see Figs. 1, 5, and 16) thereof removed, and has substantially straight parallel grooves I0" cut therein instead of spiral threads, and these grooves terminate in a. depthwise cutting corresponding taper -of the 'part to be threaded.

By locating the chaser in an angular position on the chaser block, a proper clearance and lead for the thread is obtained and by using this angular location of the' chaser, the chasers can be ground independently and not in sets of four or more which Would be necessarywere the chasers provided with spiralV grooves. In other words, if the chasers-were provided with spiral grooves, this would require that the entire set of chasers be ground onthe cutting edgeexactly the same to secure the proper cutting position, and it is practically impossible for any operator to adjust them correctly. y

All of the chasers of a set are formed exactly the same but the heighth from the rear face at the point of the cutting edge will vary so that, in manufacturing these chasers, all of the chasers are .machined exactly the same until the last operation when the back faces of the chasers are ground to suit the position. of the cutting edge and, consequently, the position ofethe circular chaser end-Wise will always remain the same vwith relation to the top point of the thread. This is a very important point for, without this, the

structure would be too complicated for the average operator to set and impractical for general use. After this grinding, the top faces and cham.. fers of all of the chasers of thev set are ground olf exactly alike so that the chasers will all start to cut at the same time. l l

'I'he grinding of the back face of the chaser in relation to the circular grooves depends upon the number of chasers used in the tap. For instance, if four chasers are used, the distance between the ground back face of the chaser to the center of the groove varies one-fourth of the distance between the grooves. Where six chasers are used, the distance between the grooves or pitch is divided by six, etc.

When milling or grinding the chaser grooves, the blanks are rough milled and when-they are finish ground, the grinding operation compensates for the slight error in lead and form. Thelower diameter at the bottom of the chaser .is greater than'the diameter at the top or counof the chaser is predeterminedV according to the pitch of the thread to be cut and the diameter of the work being threaded in order to keep the diameter of, the circular chaser as large as possible. -!I'l1erefore, to'obtain the proper position 5 of the chasers, each chaser is ground during the last operation on its back face to suit the particular position of the cutting edge in the tap body,

a little more being ground off theback'of one kchaser than olf the back 'of another (See Figs. 12 10 to 1 5). 'I'his grinding, however, is in a perfectly straight direction or plane anddoes not give the angularity of the chaser relative to the tap body as this is obtained by the angularity of the front face of the chaser blocks, but it does give the dif- 15 ferent positions of the chasers (as shown in Figs.

' l2 to l5, wherein it will be noted that, in Fig.

l2, the distance between the lines I--2 is less than it is between -the lines 3-4 in Fig. l5, the letters A and B showing how the grinding gradu- 20 ally varies in the several chasers of the set) 'I'he front face of each chaser block may be provided, in practice, `centrally thereof with a forwardly extending, exteriorly ground ring or annular flange or pilot I4 -.(see Fig. 16), for the 25 reception of a similarly'formed interiorly ground s'urface I5 located on the outeror rear side of the serrations I6 of the chaser I0. 'Ihese two ground surfaces form means for properly positioning and supporting the chaser on the block 30 and this pilot is ground closely to lit within the chaser and is provided with a circular serrated opening I'I for the reception of a stepped serrated bushing I8 having a set of serrationsthereon, for instance 1/64th of an inch apart as at 35 I9., This bushing also-has an integral part of larger diameter in front thereof having serra-. tions thereon, for instance Blind of an inch apart as at 20. 'I'he chaser III has its back face provided with a serrated circular opening 2| corre- 40 .sponding to the serrations of the larger bushing and these several parts, the chaser, the detachable and rotatable two-section bushing and the chaser block are secured together by a screw or bolt 22 having a counter-bored front end for the reception ofa suitable tool to release the chaser `fromv its block, the screw being left-handed whereby the cuttin'gA of the chaser will tighten the screw. By `means of this or a similar combination of serrations, not only is the setting and 60 .grinding of the chaser facilitated but the turn- Aset in the proper position for cutting.

, AEach chaser is preferably counter-bored at its front end, as at 23, forming a flanged chamber 23' and this not only provides a chip clearance 65 when the chaser is cutting but permits the proper `grinding of the chaser so that it will cut properly.

The cut-away or removed segmental portion I0" along the length of the chaser forms a cutting edge with which ,the counter-bored front end in- 70 tersects while the serrated opening in the back of the chaser is of less diameter than the counter-bored opening' and does not intersect the cutting edge.

From the'foregoing, it will be seen that if a 75 bushing were used having only one set of serrations, for instance, 'zi-,nd of an inch apart, which wouldbe necessary in order that theynot be too iine to support the chaser, then the chaser would have to have its cutting edge ground of! 2nd of an inch each time it was ground, but by having a bushing of two diameters with diiierent circumferentially spaced or graduated serrations, the result is that if, for. instance, the number of serrations on the smaller bushing is less or approximately one-half of the number of serrations on the larger bushing, the chaser can be ground oi 1/64th of an inch eaclrtime instead of 2nd of an inch. l In setting the chaser to a new position, the

bushing is moved clock-.wise one serration in the chaser block. The chaser is then set back antiswiveled disk 25;

clockwise one serratlon. Now, if the smaller bushing has thirty serrations and the larger has forty serrations, this eliminates a full serration movement. In other words, there is a ratio 'of practically four to one. 1-

It will thus be seen thatan improved tap is provided having circular chasers of improved form and construction together with improved means for supporting them, which supporting -means includes means for predetermining the exact amount to be ground oi the chaser at each grinding thereof while insuring not only long life to the chaser but an accurate setting of the chaser to correspond with such grinding.

Among the numerous advantages of this improved circular chaser is not only the longer life thereof as compared with the ordinary form of chaser because there are quite a few inches of' periphery provided for grinding, but the chaser grooves can be readily circularly ground, the cutting edge is protected when thedie is collapsed as the cutting edge is rolled away from the chip instead of dragging through and the heat is carried away from the cutting edge rapidly due to the large cross section of the chaser. The chaser can be readily made in a screw machine and has a natural "clearance similar to a milled chaser. No backing on is required. The cutting edge can be readily sharpened-and the chaser can be readily taken out and returned, and there is a reduction in the stock or number of chasers required to be carried on hand. Furthermore, the chasers can be used for right and left handjthreads by simply changing' the angle of the chaser block slide opposite to that for right hand thread cutting. It will be understood, ofturse, that the coarseness of the grooves of the circular chaser can be varied as may be desired.

The lever mechanism As the sleeve or body 2 is fed forward with its chaser I0, the sleeve l is carried along and the chasers I0 are fed into the work or pipe to be threaded. On this sleeve 2 is attached a yoke 24 (see Figs. 1 and 10). In this yoke 24 is located a swiveled disk 25 and in this disk is mounted the end oi a lever 26, the inner eud of which is turned round to t into a hole in this In this lever are two holes 21-A and 2-'IB, one or the Othercarrying a pin 29. This pin extends through two arms or bars 29 and 30 having openings 21e and 21d corresponding to those .in the lever 26' (seeFigs. 10 and 1l), and these arms are secured to the core shank 3 by two clamps 3l and 32 (seeFigs. 2 and 9). To obtain a correct taper the fullv length of the thread, it is necessary that the control pointso! the lever 29 travel in parallel lines with the center of the tap. Therefore, at the upper end or top pivot point of the lever 26, the housing- I is provided with a slot 33 (see Fiss. l, 3, 4 and 8) for the reception of a -block 34 (see Fig. 10),` which block-is secured to the housing by screws.l

CII

v 35 and 33` projecting through and working in elongated slots 31 and 39 -inthe housingisee Flgs.-1,3and4). v

' In the block there is a pin 39 having a round ro; shank and a square head and this round shank allows the pin topivot on its own center while the square head iits into a long slot 40 (see Fig. 10) in the lever 29. Thus, although the end' of the lever 26 mves in an arc, the control point 1-5 f or pin 39 movesin a parallel line with the center line or axis of the tap. -v

The center C of the disk 25 is held in the same position and,l only has a circular motion while the l tap is threading so that the distance from the 20.-

the swivel disk 25, moves' in an arc, but the end 30" of this lever 26 can move endwise in the hole of the swivel disk. The pin 28 in either hole 21-A or 2'I--B also moves in a-parallel line .with the center lineor axis of the tap as it is held in position by its iltting into the holes of the arms 35i 29 and 30.

Thus, as the tap is fed into the work, the described parts will not change their relative positions until the trip ring 4I carried at the front of the housing I contacts with the face. of the 40' e pipe, coupling or work to be threaded. Any

mechanical means can 'be used to stop the forward travel of the housing I in place of'vv the trip As the tap keeps feeding into the work, withfi5 the housing I stopped'ythe end of the lever 26 at point 39 is stopped causing the pin 28 in either oi lthe holes 21-A or 21-B to slow up its forward travel in the ratio of the difference in the spacing oi the pin 39 to the pin 21-A or 21,-B '50 1 and center of the swiveled disk 25 at C. This, in

turn, holds back the forward travel of the arms 29 and 3l! and core shank 3 together with the tapered core 4. When the core 4 and its shank 3 are thus held back from the full forward travel of the tap body 2, the chaser blocks 8, together with the chasers I 9 are allowed to push toward the center by the cutting action and if the cutting action does not accomplish this, the blocks are pulled in toward the center of the tap by the interlocking connections between the blocks 8 and the core 4, thereby obtaining a tapered thread. The tapers, threaded with this particular tap the way it is shown, are ..0625" included taper per 1", or .03l25" included taper per 1".

The core piece 4, as shown in the drawings.

I has a taper 1/2" included taper to 1". This is eight times the taper for .0625" includedtaper to 1".' and sixteen times the taper for .03125" 'included taper to 1". That is usually required 70- on taper pipe threads. Therefore, the ratio of the difference from the pivot point 39' to pivot point C of the lever 26 will, in practice, be sixteen times the distance from point C to the pivot point 21-A and 'tight times the distance from 7,5',-

point C to pivot point 21-13. Therefore, as the tap feeds into the work, the core 4 is held back when threading .0625 taper per inch threads) M," for every 1" the chasers are fed into the 5 work and, when threading (.03125" taper per inch threads) the core piece isy held back for every 1" that the chasers are fed into the g work. With this lever type of control, by having two 1:0 or more holes as 2'I-A and 2'I-B for the location of the pin 28 in the lever 26 and arms 28 and 38 ofthe core piece 3, a number of tapers under positive controland also a very ne adjustment of taper can be obtained by merely loosening the two screws 35 and 36 and moving theblock 34 so as to adjust the pin38 at the outer end of the lever.

To obtain the proper control of the taper action through the lever and tapered core, the action has been so designed that the ratio of movement is accurate from the start of the threading to the inish thereof. This is obtained by keeping the control and locating points of the lever in proper location. `As will be observed, the three points are always equidistant from the axis of the tap,

.and thethree points are always in line with each other. The tripping means To collapse the chasers out of the threaded work when the required length of thread has been cut, a trip dog 42 is provided secured to the housing I by a screw 43. 'I'his dog and screw can be adjusted in an elongated slot 43 to provide forvarious lengths of thread (see Fig. 6).

' As shown in the drawings; thedog is set to cut the maximum length which is approximately 5%" on this size of tap.

- 'I'he body or sleeve 2 carries a spring actuated 4o trip dog 44 having a roller 45 mounted on a pin 48 and these parts hold a trip plunger 41 back in a suitable slot 48.

0n this trip plunger 41 is a block48 secured in Place by a screw 58 and this block 48 contacts I with the dog 42-as the tap feeds into the work so that, when the required length of thread has cut, the dog 42 contacting with the block 49 stops the-,forward travel of the tripplunger plunger iststopped, the

ward until it passes the inner ends of an `ad`- justing ring 53 mounted on the-end lof the sleeve I and thereby allows this adjusting ring, and

55 thereby the sleeve I' of the tap to be pulled back by the tension spring 54. This spring is held by a pin 55 in the body and by a pin 56 in the core carried thereby. are drawn in toward thecen r of .the tap.

On this size oftap, the core 4 moves back 5%" 0n collapsing action and this draws each chaser block 8 inward 135'( which is more than enough to clear the threads in the piece.

Taper adjusting means v5 The adjus/tment for taper from' taper per to C relative to points 2'I-A a pivot for the lever 6I of the elongated slot inthe sleeve l so that pres- 70 foot to V4" taper per foot is obtained simply by transferring the pin 28 from the'hole 2I-A to hole 2'I-B in the arms 28 and 30.

Fine adjustment for taper can be -made by changing the 'position of the block 34 in the hous ing I. We have designed this part so as to move this block 34 1%" on this size of tap and this 1%" movement allows us to move the block outward and get a, greater ratio from point, 38

or 21-B, and by 14 moving the block 34 inward, we get a lesser ratio from point 39 to point C relative to points 21-A cr 2'I-B'. This, o f course, changes the taper and in this size of tap for %'v' taper we get a ne adjustment of .0032" on taper per inch and 15 .0064 adjustment on taper per inch threads. This ne adjustment is desirable as some customers desire to hold the adjustment to a. plus dimension and others to a minus; also variations ln taperfor various reasons can be taken care of. 20

\ Diameter adjusting means Adjustment for diameter is obtained by moving the threaded adjusting ring 53 held in place by a lock nut 51 on sleeve I. The tension spring 25 54 by means of the core shank 3, the arms 29 and 88, yoke 24 and sleeve I holds the adjusting ring 53 back against the dog 44 and thus maintains these parts in proper co-operative relation.

When the adjusting ring 53 is turned, this per- 30 mits the sleeve I' together with the yoke 24, arms 28 and 38, core shank 3 and core 4 to change relative positions to the chaser blocks 8 and when the core 4 changes its position with its tapered' slots interlocked with the tapered slots of the 35 Chaser blocks 8, these blocks are necessarily adjusted inwardly or outwardly.

The adjustment on these ytaps is approximately .062 large and small or 1A," full adjustment in diameter. 40

to reset the tap.

A fork or some other stop can be attached to the machine so that the rearward travel of the housing I is stopped. A plate or ring 58 is shown contact with. As the tap moves out or rearward,

'a closing block 58 secured to the sleevel y'I' by far by reasonof the screw heads 58.

A s before stated, the coil spring-54 holds the adjusting ring sa back againsn the mp block 44 60 by means of the sleeve I', yoke 24, arms`29 and 38 and core shank 3.

'I'he tap can also be reset by a hand resetting lever 8| inserted through an elongatedfslot in the housing I and an elongated slot in the, sleeve I 55 and into a bushing 82 carrying a pin 63 of the sleeve 2 (see Fig. 17). The lever has a slot in the end to slip over the pin 63 and this makes to act, against the end sure on the lever will'cause the sleeve -I to move into position in order to allow the trip block to reset itself. j

From the foregoing it will be seen that, in this improved tap, not only 'have the number of parts 7'5 been reduced to a minimum for threading various diameters of pipe but the adjustment of the tap very much simplified. For instance when it is desired to change the length of the thread to bel cut, it is only necessary to move the trip stop 42 by loosening the screw 43 while the adjustment for a diameter of la" is provided for by merely looseningthe lock nut 51 and turning A eter-seven interchangeable nose pieces are used for /8" to 13%". The core piece is-changed so that the proper 'number of chasers can be used- 6 for 6.5/8" to 81/8'.' 8 for 8%" to 9% 10 for 10%" to 13%" .x The corepieces are also made larger in diameter for the larger pipe--three core pieces being used for 65/8" to 13% This improved tap can be used with either circular chasers or the ilat-hobbed or milled chaser It to be understood that, by'd'escribingin detail herein. any particular form, structureV or arrangement it is not intended fto lmitthein'vention beyond the terms of the several claims or the requirements -of the prior art.

Having `thus explained the nature of our said invention and described a way of constructing and using the same, although without attempting to set forth all of the forms in which it may be made, dr all of the modes of its use, we claim:

1. A tap comprising a housing, a body, a sleeve thereon shiftable axially with and independently of the body, a core shiftable relativeto the body and having a tapered head, radially shiftable chasers carried by the body and connected with the tapered head, means pivotally connected with the sleeve and housing, and means connect-l` ly of the body, a core shiftablerelative to the body and having a tapered head, radially shiftable chasers carried by the body and connected with the tapered head, means pivotally connected with the sleeve and housing, and means connecting said means withthe core and having pivotal connection with said rst means spaced from its pivotal connection with the sleeve whereby on the stoppage of the forward travel of the housing, the core is retarded thereby to eiect a tapered threading of the work in the ratio of the difference between the space of the pivotal point of said rst means with the sleeve andthe pivotal point thereof with said second means.

3. A tap comprising a housing, a body, a sleeve thereon shiftable axiallywith and independently of the body, a core shiftable relative to the body and having a-tapered head, radially shiftconnections moving in parallel lines with the able chasers carried by the body -and connected l with the tapered head, means pivotally connected' with the sleeve and housing, and means connecting said means with the -core and having pivotal connection 'with said first means spaced 5. from its pivotal connection with the sleeve whereby on the stoppage of the forward travel of the housing, the core is retarded thereby to effect a taperedV threading of the work, all of said pivotal axis of the core.`

4. A -tap comprising a housing, a body, a sleeve thereon shiftable axially with and independently of the body, a core shiftable relative to the body and having a tapered head, radially shiftable chasers carried by the body and connected with the tapered head, means pivotally. connected with the sleeve and housing, and means connecting said means with the core and havin'g pivotal connection with said first means spaced from 20 its pivotal'connection with the sleeve whereby on the stoppage of the forward travel of the housing, the core is retarded thereby to effect a tapered threading of the work in the ratio of the difference between the. space of the pivotal point 25 ofsaid first means with the sleeve and the pivpivotal connection withl the sleeve whereby on the stoppage of the forward ytravel of the housing, the

otal 'point thereof with'said second means, all of said pivotal connections moving in parallel lines with the axis of the core.

` 5. A tap comprising a housing, a body, a sleeve 30' 1 thereon shiftable axially with and independently of the body, a core shiftable relative to the body and having a tapered head, radially shiftable cir-I cular chasers carried by the body andv connected with the tapered head, means pivotally connected 35 with the sleeve and housing, and means connecting said'means with the core and having pivotal connection with said vfirst means spaced from its core is retarded therebyl to eilect a tapered threading of the work. f

6. A tap comprising housing, a body, a sleeve thereon shiftable axially with and independently of the body, a core shiftable relative to the body 45 and having a tapered head, radially shiftable chasers carried by the body and connected with the tapered head, means pivotally connected with, the sleeve and adjustably pivotally connected with -the housing, and means connecting said means 50 with the core and having pivotal connection with said first means spaced from its pivotal connection with the sleeve whereby on-the stoppage of the forward travel of the housing, the core is retarded thereby to eect a tapered threading 55 of the worE. v

thereby to effect a tapered threadingofthe work. 70v

8. A tap comprising a housing, a body, a sleeve thereon shiftable axially with and independently -of the body, a' core shiftable relative to the body and having a taperedhead, .radially4 shiftable chasers carried by the body and 'connected with 1| the work.

means with the c'ore and having spaced interchangeable pivotal connections with said first means spaced from its pivotal connection with the sleeve whereby on the stoppage of the forward travel of the housing, the core is retarded thereby to eect a tapered threading of the work in the ratio of the diiference between the space of the interchangeable pivotal point of said rst means with the sleeve and the pivotal point thereof with the second means.

9. A tap comprising a housing, a body, a sleeve thereon shiftable axially with land independently of the body, a core shiftable relative to the body and having an interchangeable tapered head, radially shiftable blocks carried by the body and connected with the tapered head, chasers carried by the blocks,- means pivotally connected with the Ysleeve and housing, and means connecting said means with the core and having pivotal connection with said rst means spaced from its pivotal l' connection with the sleeve whereby on the stoppage of the forward travel of the housing, the

pivotal connectionl of said rst means with the sleeve and the coreare retarded'thereby to effect a tapered threading of the work.

10. A tap comprising a housing, a body, a sleeve thereon shiftable axially with and independently the tapered head, a lever pivotally connected with the sleeve and housing and passing through the core, and arms connecting said lever with the core and having pivotal connection with said lever above and spaced from its pivotal connection with the sleeve whereby on .the stoppageot the forward travel of'the housing, the core will be retarded thereby to eifect a tapered threading of 11. A tap comprising Aa housing, a body,a sleeve thereon shiftable axially with vand independently of the body, a core shiftable relative to the body and having a tapered head, radially, shiftable chasers carried by the body and oon` nected with the`tapered head, a lever pivotally connected with the sleeve and housing and passing through the core, and arms connecting fsaid lever with the4 core and having spaced interchangeable connections with said lever above and spaced from itsnpivotal connection with the sleeve whereby on the stoppage of the forwardtravel ofthe body, the core will be -retarded thereby to eiect a tapered threading of the work.

12. A tap comprising a housing, a body, a sleeve thereon shiftable axially with and independently of the body, a core shiftable relative to the body land having a tapered head, radially shiftable .chasers carried by the body and connected vwith the tapered head, a lever., pivotally connected with the sleeve and ,housing and passing through the core and arms connecting saidv lever with the cf having spaced interchangeable connectionswith said`lever above and spaced from its pivotal connection 'with the sleeve whereby on the stoppage of the forward travel of the housing, the core will be retarded thereby to effect a tapered threading of the work in the ratio of the difference between the space of the pivotal point of said lever with the sleeve and the interchangeable pivotal points thereof with the arms.

13. A tap comprising a housing, a body, a-

sleeve thereon shiftable axially with and indey' pendently of the body, a core shiftable lrelative to the body and having an interchangeable tapered head, radially shiftable blocks carried by the body and interlocked with the tapered head, circular chasers carried by the blocks, a lever pivs.

otally connected with the sleeve and passing through the core and adjustably pivotally connected with the housing, and arms connecting said lever with the core and having spaced interchangeable pivotal connections above and spaced 10 from the pivotal connection of said lever with the sleeve whereby on the stoppage of the forward travel of the housing, the pivotal connection of the 'lever with the sleeve and the core are retarded in the ratio of the difference between the 15 space of the pivotal point of said lever with the sleeve and the pivotal points thereof with the arms, thereby to effect a tapered cutting of the thread, all of said pivotal connections moving in parallel lines with the axis of the core.

14. A tap comprising a housing, a body, a sleeve thereon shiftable axially with and independently of the body, a core shiftable relative to the body and having a tapered head, ra-

and connected with the tapered head,4 means A pivotally connected with the sleeve and housing, means connecting said means with the core and having pivotal connection with said nrst means spaced from its pivotal connection 30 with the sleeve whereby on the stoppage of the forward travel of the housing the core is retarded 4thereby to effect a tapered threading of the work, and 4means for collapsing the chasers away from the thread.

15 A tap comprising a housing, a body, a sleeve thereon shiftable axially with and independently of the body, a core shiftable relative to the body and having a tapered head, radially shiftable chasers carried by the body and connected 40 with the tapered head, means pivotally connected with the sleeve and housing, means connecting said means with the core. and having pivotal connection with said flrst means spaced from its pivotal connection with the sleeve whereby; on the stoppage of the 'forward travel of the housing the core is retarded thereby to effect a tapered Y threading of the work, and adjustable means `for collapsing the chasers away from thethread and adjustable to permit the cutting of various lengths of thread.

16. A tap comprising a housing, a body, a sleeve thereon shiftable axially with and independently of the body, a core shiftable relative to the body vand having a tapered head, -radially shiftable 5.5

chasers carried by- 'the body and connected with the tapered head, means pivotally connected with the sleeve and housing, means 'connecting said means with .the core and having pivotal connecnon with said first means spaced from its pivotal 00 l connection with the sleeve whereby on the stoppage of the forward travel of the housing the core is retarded thereby to effect a tapered thread. I

ing of' th`e work, and adjustable ,means for col-a lansing the chasers away from the thread and adthereon shiftable axially with and v'independently of the body, a core shiftable relative to the bodyand having a tapered head, radially 'shiftable 75 I the tapered head, means pivotally connected with the sleeve and housing, meansconnecting said means with the core and having pivotal connection with said rst means spaced from its pivotal connection with the sleeve whereby on the stoppage of the forward travel of the housing the core is retarded thereby to eil'ect a taperedthreading of the work, and means for adjusting the `diameter of the tap. I

18. A tap comprising a housing, a body,a sleeve thereon shiftable axially with and independently of the body, a core shiftable relative to the body and having a tapered head, radially shiftable chasers carried by theV body and`connected with the tapered head, means pivotally connected with the sleeve and housing, means connecting-said means with the core and having pivotal conneci tion with said rst means spaced from its pivotal connection with the sleeve whereby on the stoppage of the forward travel o. .the housing the core is retarded thereby to eect a tapered thread-V ing of the workand means for adjusting the diameter ofthe tap and comprising a threaded adjusting ring mounted on the sleeve.

19. A tap comprising a housing, a body, a sleeve thereon shiftable 'axially with and independently of the body, a core shiftable relative to the body and having a taperedhead, radially shiftable chasers carried by the body and connected with the tapered head, means pivotally connected with thesleeve and housing, means connecting said means with the core and having pivotal connection with said vilrst means spaced from 'its pivotal connection with the sleeve whereby on the stoppage of the forward travel oi the housing the core is retarded thereby to 'eieot a tapered threading of the work, and means fm resetting.

the tap.

20. A comprising ahousing, a body, a

sleeve thereon shiftable axially with and iridependently of the body, a core shiftable relative to the body and having an interchangeable ta.- pered head, radially shiftable blocks carried by the body and interlocked with the 'tapered head, circular chasers carried bythe blocks, a lever pivotally connected with the sleeve and pwing through the core and adjustably pivotally connected with the housing, arms connecting said lever with thecore and having spaced interchangeable pivotal connections aboveand spaced from the pivotal connection of said lever with the v sleeve whereby on the stoppage of the forward travel of the housing the pivotal connection of the leyer with the sleeve and the core are retarded in the ratio oi the difference between the space of the pivotal point of said lever with they thread, all of said pivotal connections moving in parallel 'lines with the axis of the core, means for collapsing the chasers away from the thread,- 5 means for .adjusting the diameter of the tap, and means for resetting the tap. A 5

` 21. A tap comprising an axially shiftable core having a tapered head, a sleeve, a -sleeve comprising a body and a head located between said ilrst l0 sleeve and the core, radially shiftable chasers carried by the head of the body and connected with the v tapered head of the core, "means having remote 'spaced pivotal connections, one of such pivotal connections being with said iirst sleeve, l5 y carried by the head of the body and connected with the tapered head of the core, means having remote spaced pivotal connections, one of such pivotal connections being with said firstsleeve. and means connecting said means with the core and having an adjustable pivotal connection with said irst'means spaced Vvfrom its pivotal connec-` tion with the sleeve whereby, on the stoppage of the forward travel of one of itsspaced pivotal connections, the core is retarded thereby to eiect a tapered threading of the work, in the ratio of the difference between the space of thepivotal point oef said iirst means with the sleeve and the pivotal point'thereot with said second means.

23. A tap comprising fan axially shiitable core having a tapered head, a sleeve, a sleeve comprising a body and a head located betwn saidiirst sleeve and the core, radially shiftable chasers carried by the head of the ybody and connected with the tapered head of the core, means having remote meced adjustable pivotal connections, one of -such pivotal connectlons'being with said nrst sleeve, and means connecting said means with the core and having pivotal connection withsaid 59 ilrst means spaced from its pivotal connection with the sleeve whereby, on the stoppage of the forward travel o! one of its spaced pivotal conneci tions, vthe core is retarded, thereby to effect a tapered threading of the work.

ALFRED E. DRISSNER. `WILLIAM J. HOGG. 

